A scanning type image display optical system of the present invention comprises: a reflecting surface; an optical scanning unit which forms a two-dimensional image on the reflecting surface by light scanning; and an ocular optical system which leads light from the two-dimensional image formed on the reflecting surface to an observer.
|
1. A scanning type image display optical system comprising:
a reflecting surface;
an optical scanning unit which forms a two-dimensional image on said reflecting surface by light scanning; and
an ocular optical system which leads light directly reflected from said reflecting surface to an observer,
wherein said reflecting surface has a curvature and is disposed between said optical scanning unit and said ocular optical system in an optical path, and directions of normal lines of said reflecting surface differ depending on the positions of said reflecting surface so that the principal reflecting direction of light made incident upon said reflecting surface from said optical scanning unit becomes a direction toward said ocular optical system irrespective of the incident positions on said reflecting surface.
2. The scanning type image display optical system according to
a light source which emits modulated light in response to an image signal and the emitted light is made incident upon said optical scanning unit.
3. The scanning type image display optical system according to
4. A scanning type image display apparatus comprising;
a scanning type image display optical system according to
a drive circuit which drives said optical scanning unit.
5. An image display system comprising:
an image display apparatus according to
an image providing apparatus which provides image information for displaying a two-dimensional image by light scanning of said optical scanning unit, to said image display apparatus.
|
|||||||||||||||||||||||||
This application is a DIV of application Ser. No. 10/236,444 filed Sep. 5, 2002, U.S. Pat. No. 6,822,773.
1. Field of the Invention
The present invention relates to a scanning type image display optical system comprising an optical scanning unit which forms a two-dimensional image by light scanning and a scanning type image display apparatus.
2. Description of the Related Art
With the advancement in the performance of the semiconductor technology, the data communications environment has also become more sophisticated, and portable information terminals have progressed rapidly. In such a situation, an ever-greater advanced display of information by portable information terminals has been demanded, and an improvement in display resolution of portable information terminals has been demanded, therefore, head mounted displays (HMDs) have come to receive great attention.
Most of the current HMDs are constructed such that a transmission type liquid crystal display is used as an image display element and images displayed on the liquid crystal display are observed by an observer as a virtual image through an ocular optical system.
A transmission type liquid crystal display is illuminated by a back illuminating optical system such as a fluorescent tube, however, transmittance of the liquid crystal display is on the order of several percent and utilization efficiency of light is very low. Therefore, power consumption is great and for use as a display unit of a portable information terminal, utilization efficiency of light must be improved.
On the other hand, techniques relating to a display apparatus using no such two-dimensional image display element as a liquid crystal display have been disclosed and suggested in U.S. Pat. No. 5,467,104, Japanese Laid-Open Patent Publication No. 2000-111829, etc. U.S. Pat. No. 5,467,104 has disclosed a technique for forming an image directly on a retina via an optical system by scanning of R (red), G (green), and B (blue) light in the horizontal direction and vertical direction.
In addition, in Japanese Laid-Open Patent Publication No. 2000-111829, a scanning type image display apparatus which uses a beam from a beam source for two-dimensional scanning and leads the beam into an eyeball via an integrated reflecting member disposed in front of the wearer's (observer's) eye.
However, in the scanning type image display apparatus disclosed in the above U.S. Pat. No. 5,467,104, since it is required that light scanning is performed at a very high speed, a very small-sized device is used for a light scanning part constituted by a mirror or the like. Accordingly, a beam used for scanning becomes extremely thin, thus the diameter of the beam at the observer's pupil position becomes very small.
As a method for expanding such a small exit pupil diameter, techniques disclosed in U.S. Pat. No. 5,701,132 and U.S. Pat. No. 5,757,544 exist. In U.S. Pat. No. 5,701,132, by transmitting a scanning beam which has formed an intermediate image having a curvature through expanding members such as a lens array and a diffusion plate, the divergence angle of rays after transmission through the expanding member is expanded.
In addition, in U.S. Pat. No. 5,757,544, although this image display apparatus is not a scanning type, by transmitting, through a diffusing plate, light after being made incident into an image display element such as an LCD (liquid crystal display) illuminated by parallel light rays, the exit pupil is similarly expanded.
However, in these constructions disclosed in US patents, since the transmission-type exit pupil expanding members are used, the optical path becomes long, resulting in a large-sized apparatus.
A scanning type image display optical system of the present invention comprises: a reflecting surface; an optical scanning unit which forms a two-dimensional image on the reflecting surface by light scanning; and an ocular optical system which leads light from the two-dimensional image formed on the reflecting surface to an observer.
The features of a scanning type image display optical system, a scanning type image display apparatus, and an image display system of the present invention will be more fully revealed from the following detailed description of embodiments by reference to the drawings.
Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
In addition, in the light source control circuit 109, an image signal from an image providing apparatus 400 such as a personal computer, a video player, or a DVD player are to be inputted, and the head mounted display and the image providing apparatus 400 compose an image display system.
The light source control circuit 109 drives the light source 101 in response to the image signal from the image providing apparatus 400 and causes the light source 101 to emit a modulated beam. Namely, in the present embodiment, beam to be emitted from the light source 101 is directly modulated.
The beam from the light source 101 is made incident into an optical scanning unit 103 via a first optical system 102. The optical scanning unit 103 is connected to a scanning control circuit 110 and is controlled synchronously with the light source 101. This optical scanning unit 103 is capable of deflecting the incident beam into a two-dimensional direction. Herein, in
The beam scanned by the optical scanning unit 103 is condensed at respective arrival points on a reflecting member 105 via a second optical system 104. By scanning the modulated beam from the light source 101, a two-dimensional image is formed on a reflecting surface of the reflecting member 105. The light source 101, the first and second optical systems 102 and 104, and the optical scanning unit 103 compose a scanning optics 140.
The reflecting member 105 is composed of a screen or the like and reflects, irrespective of the incident positions, the beams 111a, 111b, and 111c made incident upon its reflecting surface in the direction shown with 111a′, 111b′, and 111c′, that is, in the direction toward an ocular optical system 107.
The reflected beams 111a′, 111b′, and 111c′ are made incident, via the ocular optical system 107, into a pupil 113 of an observer's eye 108.
The beams are made incident into the pupil 113 of the observer form, on a retina 114 of the eye 108, images 115a, 115b, and 115c corresponding to condensing points 112a, 112b, and 112c on the reflecting member 105. As a result, the it can be observed, via the ocular optical system 107, a two-dimensional scanned image formed on the reflecting member 105.
The optical scanning unit 103 (unillustrated in
In the present embodiment, as shown in
118a, 118b, and 118c denote principal rays of beam scanned by the scanning optics 140 at certain times, respectively. Herein, the principal rays 118a, 118b, and 118c are rays that have been exited from an apparent scanning point 117.
Owing to a condensing action of the second optical system 104, the beams including the respective principal rays 118a, 118b, and 118c form condensing points 119a, 119b, and 119c substantially on the reflecting surface (or in the vicinity of the reflecting surface) of the reflecting member 105 and are reflected by the reflecting member 105 and deflected so as to become reflected including rays 118a′, 118b′ and 118c′, respectively.
The respective points on the reflecting surface of the reflecting member 105 have an action to deflect the beams so that the principal rays 118a′, 118b′ and 118c′ reflected on the reflecting member 105 become approximately parallel to each other and are made incident into the ocular optical system 107 (unillustrated in
By this construction, at the respective points located on the reflecting member 105, most of the rays which have been made incident can be deflected into a desirable direction, namely, in a direction for incidence into the ocular optical system 107 (unillustrated in
The reflected rays 118a′, 118b′, and 118c′ (in
Then, the principal ray 118b reflected on the reflecting member 105 reflects as shown by 118b′. Furthermore, its marginal rays 118M and 118M′ reflect as shown by 118R and 118R′.
Furthermore, expression of the diffusing action on the reflecting member 105 can be realized by a diffusing structure having a minute uneven shape, a diffraction grating structure or the like. Even if a diffusing action is given to the reflecting member 105, since the scanning beam is condensed substantially on the reflecting surface of the reflecting member 105, little deterioration in resolution occurs.
According to the construction as in the above, by folding the optical path by the reflecting member 105, an image display optical system which is, while being a scanning type, small in size, moreover, can expand a pupil, and furthermore, has high resolution, can be realized.
In addition, a construction for leading the scanned beam to an observer's eye by means of an integrated reflecting plate such as a minute Fresnel lens or the like has been disclosed in Japanese Laid-Open Patent Publication No. 2000-111829, as well. However, since no two-dimensional image is formed on the integrated reflecting plate disclosed in this publication, this is completely different in function from the reflecting member 105 of the present embodiment. In the present embodiment, a description has been given for a case where a reflective Fresnel lens is used as the reflecting member 105 having minute reflecting structures, however, a reflecting member used in the present invention is not limited hereto.
In addition, in the present embodiment, a description has been given for a case where the two-dimensional scan mode to be carried out by the optical scanning unit 103 is provided as a so-called raster scanning as shown in
As the optical scanning unit, an optical scanning unit which is the same in construction as ones mentioned as prior arts, a polygon mirror, a galvano mirror or the like can be used.
Furthermore, in the present embodiment, a description has been given for a case where a single light source is provided, however, a plurality of light sources may be provided, and furthermore, light sources of a plurality of colors such as red, blue, and green may also be used so that a color image can be displayed.
In the abovementioned embodiment shown in
In
Similar to the embodiment shown in
The beams of the respective colors from the light sources 201a, 201b and 201c are composed as one beam by a color-composing element 220 such as a dichroic prism. The color-composed beam is made incident into an optical scanning unit 203 via a first optical system 202.
The optical scanning unit 203 is connected to a scanning control circuit 210 and is controlled synchronously with the light sources 201a, 201b and 201c. This optical scanning unit 203 is capable of deflecting the incident beam into a two-dimensional direction. The light sources 201, the color-composing element 220 and, the first and the second optical systems 202 and 204, and the optical scanning unit 203 compose the scanning optics 240. And the light source control circuit 209 and the scanning control element 210 compose a control part 230.
In the drawing, 211a, 211b, and 211c denote examples of beams scanned by the optical scanning unit 203, which are condensed at respective arrival points 212a, 212b, and 212c on a reflecting member 205 via a second optical system 204. By color-composing of the modulated beams of the respective colors from the light sources 201a, 201b and 201c and scanning the color-composed beam, a two-dimensional full-color-image is formed on the reflecting member 205.
The reflecting member 205 reflects, by means of its reflecting surface, the incident beams 211a, 211b, and 211c, irrespective of the incident positions, in the direction shown with 211a′, 211b′, and 211c′. The reflected beams 211a′, 211b′, and 211c′ are made incident, via the ocular optical system 207, into a pupil 213 of an observer's eye 208. On a retina 214 of the eye 208, images 215a, 215b, and 215c corresponding to condensing points 212a, 212b, and 212c on the reflecting member 105 are formed.
As a result, the observer can take notice, via the ocular optical system 207, a two-dimensional full-color scanned image formed on the reflecting member 205.
In the present embodiment, as shown in
In
Owing to a condensing action of the second optical system 204 (unillustrated in
The respective points on the reflecting surface of the reflecting member 205 have an action to deflect the beams so that the principal rays 218a′, 218b′ and 218c′ reflected on the reflecting member 205 become approximately parallel to each other and are made incident into the ocular optical system 207 (unillustrated in
In detail, a curvature of the reflecting member 205 has been set so that the directions of normal lines (shown by alternate long and short dash lines) of the reflecting surface at the respective points differ from each other.
Furthermore, as shown in
Expression of the diffusing action on the reflecting member 205 can be realized by a diffusing structure having a minute uneven shape, a diffraction grating structure or the like. Even if a diffusing action is provided for the reflecting member 205, since scanning beam is condensed substantially on the reflecting surface of the reflecting member 205, little deterioration in resolution occurs.
According to the construction as in the above, by folding-the optical path by the reflecting member 205, an image display optical system which is, while being a scanning type, small in size, moreover, can expand a pupil, and furthermore, has high resolution can be realized.
Herein, in the present embodiment, a description has been given for a case where a curvature is provided for the reflecting surface of the reflecting member 205, and the deflecting (reflecting) direction of incident beam from the optical scanning unit 203 is controlled to become a direction toward an ocular optical system 207, however, similar to the embodiment shown in
In addition, a member having the same deflection characteristics as those of minute reflecting plates, for example, a reflective hologram may be used.
In addition, as the optical scanning unit, an optical scanning unit which is the same in construction as ones mentioned as prior arts, a polygon mirror, a galvano mirror or the like can be used.
In the present embodiment, in place of the ocular optical system as a co-axial system used in the embodiment shown in
The basic construction of the embodiment is the same as that of the embodiment shown in
In
Similar to the embodiment shown in
The optical scanning unit 303 is connected to a scanning control circuit 310 and is controlled synchronously with the light source 301. This optical scanning unit 303 is capable of deflecting the incident beam into the two-dimensional direction. The light source control circuit '309 and the scanning control circuit 310 compose a control part 330.
In the drawing, 311a, 311b, and 311c denote examples of beams scanned by the optical scanning unit 303, which are condensed at respective arrival points 312a, 312b, and 312c on a reflecting member 305 via a second optical system 304. The light source 301, the first and the second optical systems 302 and 304, and the optical scanning unit 303 compose a scanning optics 340.
By causing the light source 301 to emit a modulated beam, a two-dimensional image is formed on the surface (on multiple minute reflecting plates) of a reflecting member 305, which has been constructed similarly to the reflecting member 105 of the embodiment shown in
The reflecting member 305 reflects incident beams 311a, 311b, and 311c in the directions shown with 311a′, 311b′, and 311c′. The reflected beams are made incident, via the ocular optical system 307, into a pupil 313 of an observer's eye 308. The beams made incident into the pupil 313 form, on a retina 314 of the eye 308, images 315a, 315b, and 315c corresponding to condensing points 312a, 312b, and 312c on the reflecting member 305. As a result, the observer can observe, via the ocular optical system 307, a two-dimensional scan image formed on the reflecting member 305.
In the present embodiment, as shown in
In terms of the reflecting member 305, the directions of normal lines of the respective minute reflecting plates have been set so that the reflected beams 311a′, 311b′, and 311c′ are appropriately made incident into the ocular optical system 307. In short, the directions of normal lines of the reflecting surfaces of the minute reflecting plates differ depending on the positions of the minute reflecting plates on the reflecting member 305.
Furthermore, similar to the embodiment shown in
Herein, the ocular optical system 307 will be briefly explained. The ocular optical system is constituted by a prism member 307 which is composed of three free-form surfaces (or rotationally asymmetric surfaces including not more than one symmetric plane) as first through third surfaces 307a–307c.
When the beam 311a′ which has been reflected on the reflecting member 305 is taken as an example, this reflected beam 311a′ is made incident into the prism member 307 from the first surface 307a. Furthermore, the reflected beam 311a′ proceeds inside the prism member 307, substantially totally reflects on the second surface 307b, and proceeds toward the third surface 307c. Then, the reflected beam 311a′ reflects on the third surface 307c, proceeds again toward the second surface 307b, and then transmits through the second surface 307b, and is emitted from the prism member 307.
This emitted beam is led to the pupil 313, whereby the observer can observe a two-dimensional image formed on the reflecting member 305.
As in the present embodiment, by constructing the first through third surfaces 307a–307c, which are optical surfaces composing the prism member (the ocular optical system) 307, with free-form surfaces (rotationally asymmetric surfaces), decentering aberration and the like can be corrected, thus it becomes possible to allow the observer to view a satisfactory image.
According to the construction as in the above, by folding the optical path by the reflecting member 305, an image display optical system which is, while being a scanning type, small in size, moreover, can expand a pupil, and furthermore, has high resolution can be realized.
Herein, in the present embodiment, a description has been given for a case where the reflecting member 305 having minute reflecting structures is used, however, a reflective hologram or the like may be used.
In addition, as the optical scanning unit, an optical scanning unit which is the same in construction as ones mentioned as prior arts, a polygon mirror, a galvano mirror or the like can be used.
Furthermore, in the present embodiment, a description has been given for a case where a single light source is provided, however, a plurality of light sources may be provided, and furthermore, light sources of a plurality of colors such as red, blue, and green may also be used so that a color image can be displayed.
In addition, in the above respective embodiments, descriptions have been given for cases where a beam to be emitted from the light source is directly modulated, however, a light flux from the light source may be modulated by an optical modulator (for example, an image display element such as a liquid crystal panel) arranged in the optical path from the light source.
In addition, in the above respective embodiments, descriptions have been given for cases where the second optical system is inserted between the optical scanning unit and reflecting member, however, a function for condensing light onto the reflecting member may be provided for the first optical system. In this case, if distortion and the like of the two-dimensional scan image formed on the reflecting member is corrected by optical corrections by the second optical system and control of the light source and the like, an optical system for expanding a virtual image on a prior optical modulator such as a liquid crystal panel can be used as an ocular optical system without modification.
As described above, according to the above respective embodiments, a two-dimensional image is formed on the reflecting surface of a reflecting member by beam (light) scanning by the optical scanning unit, and this two-dimensional image formed on the reflecting surface is observed through the ocular optical system, therefore, by folding the optical path by the reflecting member, the entire image display optical system can be downsized, although being a scanning type.
Moreover, irrespective of the beam incident positions upon the reflecting surface of the reflecting member from the optical scanning unit, the principal reflecting direction of beam is a direction toward the ocular optical system, therefore, utilization efficiency of light is high and it becomes possible to observe a bright image.
Furthermore, by providing a diffusing action for the reflecting surface, the diameter of the exit pupil of an observation optical system can also be expanded.
While preferred embodiments have been described, it is to be understood that modification and variation of the present invention may be made without departing from the sprit or scope of the following claims.
| Patent | Priority | Assignee | Title |
| 7609229, | Sep 30 2003 | Canon Kabushiki Kaisha | Image displaying apparatus |
| Patent | Priority | Assignee | Title |
| 5467544, | Sep 18 1992 | Electric sign advertising element | |
| 5701132, | Mar 29 1996 | University of Washington | Virtual retinal display with expanded exit pupil |
| 5757544, | Mar 09 1993 | Olympus Optical Co., Ltd. | Image display apparatus |
| 6281862, | Nov 09 1998 | Washington, University of | Scanned beam display with adjustable accommodation |
| JP2000111829, | |||
| JP2001027738, | |||
| JP7509326, | |||
| WO9427177, |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Oct 12 2004 | Canon Kabushiki Kaisha | (assignment on the face of the patent) | / |
| Date | Maintenance Fee Events |
| Aug 11 2010 | M1551: Payment of Maintenance Fee, 4th Year, Large Entity. |
| Oct 24 2014 | REM: Maintenance Fee Reminder Mailed. |
| Mar 13 2015 | EXP: Patent Expired for Failure to Pay Maintenance Fees. |
| Date | Maintenance Schedule |
| Mar 13 2010 | 4 years fee payment window open |
| Sep 13 2010 | 6 months grace period start (w surcharge) |
| Mar 13 2011 | patent expiry (for year 4) |
| Mar 13 2013 | 2 years to revive unintentionally abandoned end. (for year 4) |
| Mar 13 2014 | 8 years fee payment window open |
| Sep 13 2014 | 6 months grace period start (w surcharge) |
| Mar 13 2015 | patent expiry (for year 8) |
| Mar 13 2017 | 2 years to revive unintentionally abandoned end. (for year 8) |
| Mar 13 2018 | 12 years fee payment window open |
| Sep 13 2018 | 6 months grace period start (w surcharge) |
| Mar 13 2019 | patent expiry (for year 12) |
| Mar 13 2021 | 2 years to revive unintentionally abandoned end. (for year 12) |